Figure 2 . (a) Descent rate of float WMO 3902151 at cycle 41, located on the western flank of the Mid-Atlantic Ridge in the Brazil Basin. Raw values from first differences of pressure over time (black dots), values at 10 dbar intervals derived by filtering raw values with a 150-dbar lengthscale Loess smoother (black curve), and background values (red dashed line) estimated from a 2nd order polynomial fit to the filtered values vs. pressure for 1000 dbar to the bottom value. (b) Power spectrum for the Morlet wavelet transform of the residual w’ (filtered minus background) vertical velocity from panel (a) with contours at uniform intervals and the location of the maximum of the power spectrum (large red dot), disregarding values in the “cone of influence” affected by zero-padding of edge values (which has been masked with white in the figure).